Vacuum-tube circuits



Nov. 27, 1928.

D. C. PRINCE VACUUM TUBE CIRCUITS Original Filed May 4, 1925 Z Sheets-Sheet InVzntor:

Q a, m w A c g m H v Nov. 27, 1928.

D. C. PRINCE VACUUM TUBE CIRCUITS Original Filed May 4, 1923 2 Sheets-Sheet 2 "Flgifi.

Im/antor .,/m ma mJm pin 0 @M Patented Nov. 27, 1928.

UNi Eo STATES PATENT "Price.

DAVID C. PRINCE oF SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION OF,NEW YORK.

VACUUM-TUBE CIRCUITS.

Application filed May 4, 1923, Serial No. 636,696. Renewed November 30, 1927.

My present invention relates to vacuum tube circuits and more particularly to cir cuits employed with vacuum tubes for producing alternating currents from direct currents.

My present application is a continuation 1 partof my prior application Serial No. 599,919, filed November 9, 1922.

' One of the objects of my invention is to provide a simple and eflicient circuit connection for converting direct current to alternating current by means of vacuum tubes having asymmetric current conducting properties.

A furtherobject of my invention'is to provide means whereby the operation of the vacuum tubes may be controlled in such a way that the periods during which individual devices are in operation will vary in a de- '20 sired manner in accordance with variationsin the load supplied by the system.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims.

My invention itself, however, both as to its and Fig. 5 IS a representation of the relation between the currents in different tubes under varying load C0!1(lltl01lS.=

In the arrangement shown in Fig. 1 three vacuum tubes or valves 1, 2?;and 3, are indicated with connections for converting direct current to three-phase alternating current. 4 Those tubes are indicated as being of the three electrode thermionic type but my invention is not limited to use with tubes of this type as it may be carried out by means of other forms of asymmetric devices which are provided with means for controlling thefiow of currentin a desired manner. The plate circuits of valves 1,2 and 3 include windings 4C,

' 5 and 6 apd' choke inductance 7 through which current is supplied from the direct current source. 8.- The windings 4, 5 and 6 are ggop'nected in Y-and inductively related to the which supply ythree phase alternating cur g t-goaload which may be connected to he upply-conductors 12, 13 and14. The

at the expense of valve 1.

t connected secondary windings 9, 10 and load-itself may form the frequency determining element or separate frequency determining apparatus may be connected to the supply conductors. The grid potentials required for controlling the operation of valves 1, 2 and 3 may be supplied by means of primarywindings 15, 16, 17 and secondary windings 18, 19,20 arranged similarly 'to wind,

ings 4, 5, 6 and 9, 10, 11. The individual gridsare fed through ballast resistances 21', 22 and 23. The neutral points of windings 18, 19 and 20 are connected to the negative terminal of source 8 through resistance 24 and inductance 25. Windings 15,16 and 17 are 'fed from 9, 10 and 11 by variable taps 26, 27 and 28 in such a way that the phase of the grid control potentials may be varied for purposes which Willbe hereinafter explained.

In order to explain the operation of the system described assume that the frequency determining element or load connected to the supply conductors 12, 13 and 14 is in operation and is generating sine-waves of counter electromotive force. This counter electromotive force is induced inthe inductances 4, 5 and 6 and thereby applied to the anodes of valves 1, 2 and. 3. Inductance 7 will maintain substantally constant current through the valves so that when current is flowing through one valve only, as Wlll be the case during the greater portion of the time, the

impressed potential must be higher than. the counterelectromotive force by an amount sufiicient to overcome the counter electrometive force and cause current to flow.

Referrin now to Fig. 5, assume that current I is owing through valve 1 and that at time t'the grid of valve 2 is made positive so that'current can flow in valve 2. .Valves 1 and 2 are then fully conducting and there is a difference in the voltage applied to the two valves which is available to start a transfor of current from one to the other. Since 'the total current is maintained constant by reactance 7, current can flow in valve 2 only l-Iowever, 1f the current in valve 1 has not been reduced to;

zero b time t, at which it is assumed that the v0 tages of the two phases are equal the difference voltage reverses and current tends to return to valve 1. If the grid of valve 1 is made negative under these conditions at time t, the valve must absorb the inductive energy represented bythe leakage flux in both phases corresponding to the residual current. If the grid is made negative at a still later point not only will the current through valve 1 be larger but there will also be a voltage difference to be overcome.

In order that the current shall be t-ranstically reduced in the manner indicated by reason of the fact that at the time valve 2 is made conducting the counter electromotive force app-lied to the anode is greater than the impressed potential and this difference is available to stop the flow of current in the valve.

In order that one valve may be made conducting before the preceding valve becomes non-conducting the potentials applied to the grids of the valves in each phase shciuld lead the potentials in the supply circuit. This effect is secured by means of the taps 26, 27 and 28 in the arrangement shown in Fig. 1. The current in the grid circuits is maintained constant by the inductance 25 and the grid current is transferred from one valve to the succeeding one in much the same manner that the plate currents are transferred.

From an inspection of the families of curves of Fig. 5 which represent currents through the valves for different load conditions it is apparent that the lead angle, that is the angle by which the grid excitation should lead-the plate potential varies with the load and that the time of overlap during which current flows in both valves also varies with the load. It is therefore desirable, although not necessary that these values should vary with the load. By adjustment of the taps 26, 27 and 28 the lead angle can be adjusted for any given load but will not vary with the load. I

One arrangement whereby this-desired result may be brought about is indicated in Fig. v2. Inthis case series inductances 29, 30 and 31 are connected to the supply conductors 12, 13 and 14, the terminals of the transformer windings 9, and 11 being connected by variable connections 32 to points in these inductances intermediate the ends. The transformer windings 15, 16 and 17 are connected to the inductances 29, and 31 by variable connections 33. hen the load increases both the amplitude and angle of lead of the potentials impressed from transformer Y windings 15, 16 and 17 upon the grid circuits of the valves increase, and as a result the lap and lead of the conducting periods of the valves are automatically increased as desired. By suitable adjustment of the connection 32 and 33 the lap and lead may be given the desired values over a wide range of load.

In the arrangement shown in Fig. 3, each of the inductances 29, 30 and 31 forms the primary winding of atransformer having secondaries 34 to 39 the-desired variation in amplitude and lead angle with variations in load may be obtained. a

In the system shown in Fig. 4, separate primary windings 43, 44 and .45 are provided for the grid transformer and inductances 46, 47 and 48 are connected in series with these windings. The taps 26, 27 and 28 are adjusted 'to give a lead angle greater than that required and this lead angle is reduced to the properyalue by the series inductance. When the load current increases the grid current decreases. As a result the potential drop across the inductances 46, 47 and 48 decreases and the angle of lead of the potentials applied to the grids automatically increases.

Wh'ilel have shown and described the pre-. ferred ernbodiments of my invention it is ap parent that my invention is not limited to the particular embodiment set forth as many modifications in the form-of apparatus as well as in the circuit connection used therewith may be made without departing from the scope of my invention as set forth in the appended claims. 7

What I claim as new and desire to secure by Letters Patent of the United States is- 1. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windingsassociated with said primary windings, and means for impressing upon the control circuit of each valve a control potential which leads the potential of the corresponding plate circuit secondary winding.

2. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control. circuits, a source of direct current connected to the plate circuits of said valves. each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with a said primary windings. a secondary transformer winding included in each of said control circuits, and means for impressing upon each of the secondary windings included in said control circuit a potential which leads the potential of the corresponding plate circuit secondary windin 3. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, second;- ary transformer windings associated with sald primary windings, a secondary transformer winding included in each of said control circuits, a primary transformer winding associated'with each of said control circuit secondary windings and meansfor impressing upon each of said control circuit primary windings a potential which leads the potential of the corresponding plate circuit secondary windingL 4. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of Said valves including a primary winding of a transtorn'ier, second ary transformer windings associated withv said primary windings, and means for impressing upon the control circuit of each valve a control potential which is derived from the plate secondary "windings and which leads the potential of the corresponding plate circuit secondary windin I 5. The combination in a system of electrical distribution of a plurality of-electron "discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the platecircuitsof said valves including a rlmary winding of a transformer, secon ary transformer. windings associated with said primary windings, a secondary transformer winding included in each of said control circuits, and 'means'for impressing upon each of the secondary windin'gs included in said control'vci-rcuit a potential'which is derived from. the plate secondary windings and which leads the potential of the corresponding plate circuit-secondary windin 6'. The combination in a system of electrical distribution of a plurality of electron discharge valves-havin plate andcontrol circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, a secondary transformer winding included in each of said control cir prima transformer winding associated with eac of said control circuit secon'dary windings, and means for impressing upon each of said control circuit primary windings a potentialavhichis derived from the plate secondary wlndings and which leads the potential of the corresponding plate cir cuit sccondar winding.

7. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said 'to'the plate. circuits of said valves, each of the plate circuits of said valves including a primary winding (if a transformer, secondary transforn'ier windings associated with said primary windings, a secondary transformer winding included in each of said control circuits, and means for impressing upon each of said secondary windings a potential which leads the potential of the corresponding plate circuit secondary winding, and the angle of lead of which varies with the load supplied by the plate secondary windin 9, The con'ibination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said Valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, a secondary transformer winding included in each of saidcontrol circuits, a primary transformer winding associated with each of said control circuit secondary windings, and means for impressing upon each of said'control circuit primary dary winding and the angle of lead of which varies with the load supplied by the plate secondary winding; I a

f 10. Thecombination in asystem of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate. circuits of saidvalves including a primary winding of a transformer, secondary t'ansformer windings associated with said primary windings, and means for impressing windings a potential which leads the potential of the corresponding plate circuit seconupon the control circuit of each valve a control potential which is derived from the plate secondary windings, which leads the potential of the corresponding plate circuit secondary winding, and the angle of lead of which varies with the load supplied by the plate secondary windin 11. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, :1 source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer 'indings associated with said primary windings, a secondary transformer winding included in each of said control circuits, and means for impressing upon each of said secondary windings a potential which is dethcdfrom the plate secondary windings, which leads the potential of the corresponding plate circuit secondary winding and the angle of lead of which varies with the load supplied by the plate secondary windings 12. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, a secondary transformer winding included in each of said control circuits, a primary, transformer winding associated with each of said controlcircuit secondary windings, means for impressing upon each of said control circuit primary windings a potential which is derived from the plate secondary windings, which leads the potential of the corresponding plate circuit secondary winding and the angle of lead of which varies with the load supplied by the plate secondary winding. v 13. The combination in a system of electrical distributionof a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves-including a primary winding of a transformer, secondary transformer windings associated with said primary windings, and means for lmpresslng upon the control circuit of each valve a control potential whichleads the potential of the corresponding plate circuit secondary winding, and the amplitude'of whichvaries with the load supplied by the plate secondary winding. 1 I

H. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves includinga primary winding of a transformer, secondary transformerwindings associated with said I primary windings, a secondary transformer winding included in each of said control circuits, and means for impressing upon each of the secondary windings included in said control circuits a potential which leads the potential of the corresponding plate circuit secondary winding and the amplitude of which varies with the load supplied by the plate secondary windin 15. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, a secondary transformer winding included in each of said control circuits,'a primary transformer winding associated with each of said control circuit secondary windings and means for impressing upon each of said control circuit primary windings a potential which leads the potential of the corresponding plate circuit secondary winding and the amplitude of which varies with the load supplied by the plate secondary winding. 7

16. The combination in a system of electri cal distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves,-each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windingsassoeiated with said primary windings, and means for impressing upon the control c1reu1t of each valve a control potential which is derived from the plate secondary windings, which leads the potential of the corresponding plate circuit secondary winding and the amplitude of which varies withthe load supplied by the plate secondary winding. I 17. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source .of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a priwhich varies with the load supplied by theplate secondary widning. I y

18. .The combination in asystem of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to tlieplate circuits of said valves, each of the mary Winding of a transformer, secondary of the corresponding plate circuit secondary winding and the amplitude 'of which varies with the load supplied by the plate secondary winding. t

19. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each ofthe plate circuits of said valves including a. primary winding of a transformer, secondary transformer windings associated with said primary windings, means for impressing upon the control circuit of each valve a potential derived from the plate secondary windings, and means for adjusting the phase of the potential impressed upon each control circuit.

20. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, means for impressing upon the control circuit of each valve a potential derived from the late secondary windings, and means for adjustin the phase and amplitude of the potential-impressed upon each control circuit. r 21. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control circuits, a source of direct current connected to Y the plate circuits of said valves, each of the plate circuits of said valves including a primary Winding of a transformer, secondary transformer windings associated with said primary windings, means for impressing upon the control circuit of each valve a potential derived from the plate secondary windings and means for varying the phase of the potential impressed upon each control circuit in accordance with the load supplied by the plate secondary winding.

22. The combination in a system of electrical distribution of a plurality of electron discharge valves having plate and control cir cuits, a source of direct current connected to the plate circuits of said valves, each of the plate circuits of said valves including a primary winding of a transformer, secondary transformer windings associated with said primary windings, means for impressing upon the control circuit of each valve a potential derived fromthe plate secondary windings, and means for varying the phase and amplitude of the potential impressed upon each control circuit in accordance with the load supplied by the plate secondary winding.

23. The combination of an electron discharge device provided with a cathode and anode and with a grid arrangedto control the current transmitted between said cathode and anode, a transformer comprisinga plurality of Windingsone of which is connected between said cathode and anode, and means connected between another of said windings and said grid for applying to said grid a potential which has its phase varied inaccordance with the load of said transformer.

In witness whereof I have hereunto set my hand this 3rd day of May, 1923.

DAVID C. PRINCE. 

